compressor maintenance

[jackfrost]

my air compressor is an old Sears "paint sprayer" model that was my dad's. I'm guessing it's early 70's vintage. I have no idea what sort of maintenance this thing needs and no product manual. I'm guessing it needs to be oiled? but I'm not sure how. it's starting to get louder the longer it runs

here's what it looks like:
http://bloomington.craigslist.org/tls/878624651.html



but mine is 150psi